KIPMU/NAOJ: Rare Encounters between Cosmic Heavyweights

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KIPMU/NAOJ: Rare Encounters between Cosmic Heavyweights

Post by bystander » Thu Aug 27, 2020 2:29 pm

Rare Encounters between Cosmic Heavyweights
Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo |
Subaru Telescope | National Astronomical Observatory of Japan | 2020 Aug 27
SDSS J141637.44+003352.2, a dual quasar at a distance for which the light reaching us
was emitted 4.6 billion years ago. The two quasars are 13,000 light years apart on the
sky, placing them near the center of a single massive galaxy that appears to be part of
a group, as shown by the neighboring galaxies in the left panel. In the lower panels,
optical spectroscopy has revealed broad emission lines associated with each of the two
quasars, indicating that the gas is moving at thousands of kilometers per second in the
vicinity of two distinct supermassive black holes. The two quasars are different colors,
due to different amounts of dust in front of them. (Credit: JD Silverman et al)

In our dynamically evolving Universe, galaxies occasionally experience collisions and mergers with a neighboring galaxy. These events can be dramatic, causing the birth of new stars, and the rapid feeding of the supermassive black hole that resides in each galaxy. It’s understood that these enormous black holes have masses millions to billions times larger than our Sun and exist in the center of all massive galaxies. As material swirls around the black hole, it is heated to high temperatures, releasing so much light that it can outshine its host galaxy. Astronomers refer to this phenomenon as a quasar.

Simulations of galaxy mergers demonstrate that sometimes quasar activity occurs at the center of both galaxies concurrently as they undergo a cosmic dance. Such a merging pair will arise as a pair of luminous “dual” quasars. While astronomers have previously found a modest number of luminous quasar pairs, they are rare, much more so than the simulations predict. The difficulty has been not having observations with both the ability to separate the light from the two quasars in close proximity and wide enough area coverage of the sky to catch these rare events in sufficient numbers.

To overcome these challenges, astronomers are taking advantage of a sensitive wide survey of the sky, using the Hyper Suprime-Cam (HSC) camera on the Subaru Telescope, to search for dual quasars. ... After a slight modification of their automated analysis tools, the team identified 421 promising cases. However, there was still the chance that many of these were not bonafide dual quasars but rather chance projections such as due to stars in our own galaxy. Confirmation required detailed analysis of the light from the candidates to search for definitive signs of two distinct quasars. ...

Maunakea Observatories Discover Three
Pairs of Merging Supermassive Black Holes

W.M. Keck Observatory | 2020 Aug 27

Dual Supermassive Black Holes at Close Separation Revealed
by the Hyper Suprime-Cam Subaru Strategic Program
~ John D. Silverman et al
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